Antenna with a concentrated magnetic field

Abstract

An antenna with a concentrated magnetic field has a main coil and at least one pair of auxiliary coils. Each of the main coil and each auxiliary coil has at least one coil conductor. Each one of the at least one coil conductor has a virtual reference plane. The at least one pair of auxiliary coils are mounted around the main coil and an included angle is formed between the virtual reference plane of each coil conductor of each auxiliary coil and that of each coil conductor of the main coil. Lines of magnetic field generated by each coil conductor of each auxiliary coil concentrate the lines of magnetic field of the main coil to orient to a corresponding virtual reference plane of the main coil, thereby solving the magnetic leakage and EMI easily occurring outside the zone of active transmission for conventional coils using electromagnetic induction.

What is claimed is: 
     
       1. An antenna with a concentrated magnetic field, comprising:
 a main coil having:
 at least one coil conductor, each one of the at least one coil conductor having at least one feed point; and 
 at least one virtual reference plane respectively defined on the at least one coil conductor of the main coil for lines of magnetic field generated by the at least one coil conductor of the main coil to be concentrated in the at least one virtual reference plane; and 
 
 at least one pair of auxiliary coils, each pair of auxiliary coils mounted on two edges of the main coil opposite to each other, wherein each auxiliary coil has:
 at least one coil conductor, each one of the at least one coil conductor having at least one feed point respectively and electrically connected to the at least one feed point of the main coil; and 
 at least one virtual reference plane respectively defined on the at least one coil conductor; 
 
 wherein an included angle is formed between each one of the at least one virtual reference plane of the auxiliary coil and each one of the at least one virtual reference plane of the main coil, and lines of magnetic field generated by the at least one pair of auxiliary coils concentrate the lines of magnetic field generated by the main coil to orient to the at least one virtual reference plane of the main coil. 
 
     
     
       2. The antenna as claimed in  claim 1 , wherein the included angle is in a range of 30° to 150°, and an optimal value of the included angle is 90°. 
     
     
       3. The antenna as claimed in  claim 2 , wherein each auxiliary coil is a quarter of the main coil in size. 
     
     
       4. The antenna as claimed in  claim 3 , wherein the at least one coil conductor of the main coil and the at least one coil conductors of each auxiliary coil pertain to an open-end type or a short-end type. 
     
     
       5. The antenna as claimed in  claim 1 , wherein the main coil and each auxiliary coil of each pair of the at least one pair are flat and rectangular and are correspondingly mounted on and connected with the respective two of the four edges of the main coil opposite to each other to constitute a box with one side open. 
     
     
       6. The antenna as claimed in  claim 4 , wherein the main coil and each auxiliary coil of each pair of the at least one pair are flat and rectangular and are correspondingly mounted on and connected with the respective two of the four edges of the main coil opposite to each other to constitute a box with one side open. 
     
     
       7. The antenna as claimed in  claim 1 , wherein each of the main coil and each auxiliary coil has two coil conductors, each coil conductor is wound with multiple turns, the two coil conductors are wound in opposite directions, the relatively outer one of the two coil conductors is wound counterclockwise, and the relatively inner one of the two coil conductors is wound clockwise. 
     
     
       8. The antenna as claimed in  claim 4 , wherein each of the main coil and each auxiliary coil has two coil conductors, each coil conductor is wound with multiple turns, the two coil conductors are wound in opposite directions, the relatively outer one of the two coil conductors is wound counterclockwise, and the relatively inner one of the two coil conductors is wound clockwise. 
     
     
       9. The antenna as claimed in  claim 5 , wherein each of the main coil and each auxiliary coil has two coil conductors, each coil conductor is wound with multiple turns, the two coil conductors are wound in opposite directions, the relatively outer one of the two coil conductors is wound counterclockwise, and the relatively inner one of the two coil conductors is wound clockwise. 
     
     
       10. The antenna as claimed in  claim 6 , wherein each of the main coil and each auxiliary coil has two coil conductors, each coil conductor is wound with multiple turns, the two coil conductors are wound in opposite directions, the relatively outer one of the two coil conductors is wound counterclockwise, and the relatively inner one of the two coil conductors is wound clockwise. 
     
     
       11. The antenna as claimed in  claim 1 , wherein each one of the at least one coil conductor of each of the main coil and each auxiliary coil is helical or spiral. 
     
     
       12. The antenna as claimed in  claim 4 , wherein each one of the at least one coil conductor of each of the main coil and each auxiliary coil is helical or spiral. 
     
     
       13. The antenna as claimed in  claim 5 , wherein each one of the at least one coil conductor of each of the main coil and each auxiliary coil is spiral. 
     
     
       14. The antenna as claimed in  claim 6 , wherein each one of the at least one coil conductor of each of the main coil and each auxiliary coil is spiral. 
     
     
       15. The antenna as claimed in  claim 7 , wherein each one of the at least one coil conductor of each of the main coil and each auxiliary coil is helical or spiral. 
     
     
       16. The antenna as claimed in  claim 8 , wherein each one of the at least one coil conductor of each of the main coil and each auxiliary coil is helical or spiral.